Compounds containing a perfluorooxyalkylene moiety generally have a very small surface free energy and, accordingly, have good water- and oil-repellency, chemical resistance, lubricity, releasing property, and antifouling property. Taking advantage of these properties, they are widely used as, for example, water- and oil-repellent agents or antifouling agents for paper or fiber, lubricants for magnetic storage media, oil repellents components for precision apparatuses, releasing agents, cosmetic, and protective coatings.
These properties, on the other hand, mean that such compounds do not stick or closely adhere to other materials, either. Even if they can be applied to a material, it is difficult to have a coating closely adhered to the material.
Meanwhile, silane coupling agents are well known as an agent which bonds an organic compound to a surface of a substrate such as glass or a cloth. The silane coupling agents have an organic functional group and a reactive silyl group, usually an alkoxy silyl group, in a molecule. The alkoxy silyl group autocondenses in the presence of moisture in air to become a siloxane and forms a coating. At the same time, the alkoxy silyl group chemically and physically bonds to a surface of glass or metal to form a durable coating. Taking advantage of these properties, the silane coupling agents are widely used as a coating agent for various substrates. Compounds based on the silane coupling agents to provide the feature of the perfluorooxyalkylene moieties on a surface of a substrate are known.
For instance, Japanese Patent Application Laid-Open No. Sho-58-167597 discloses that a fluoroaminosilane compound represented by the following formula is applied on glass to attain high water- and oil-repellency:

wherein R2 and R3 are alkyl groups having 1 to 4 carbon atoms, R1 is CH2CH2CH2 or CH2CH2NHCH2CH2CH2, h is an integer of from 0 to 8, and “i” is 2 or 3.
However, the perfluorooxyalkylene moiety of this compound is relatively short, so that the characteristics of the perfluorooxyalkylene moiety, particularly lubricity, a releasing property, and an antifouling property, are not well exhibited.
Japanese Patent Application Laid-Open No. 2000-143991 discloses perfluoropolyether-modified aminosilane represented by the following formula, as a compound having a long perfluorooxyalkylene moiety,

wherein X is a hydrolyzable group, R4 is a monovalent hydrocarbon group, R6 is a hydrogen atom or a monovalent hydrocarbon group, R5 is an alkylene group optionally interrupted by an NH group, j is an integer of from 14 to 49, and k is 2 or 3.
The perfluoropolyether-modified aminosilane has a high water- and oil-repellency on account of the terminal fluorine-containing group. However, its stain resistance and lubricity are insufficient due to the branch structure in the main chain.
Recently, there is an increasing need for technology to attain fingerprint proofness or easy removal of fouling on a surface of a display for better appearance or visibility. Thus, a material which meets these requirements is desired.
Japanese Patent Application Laid-Open No. 2003-238577 discloses a perfluoropolyether-modified silane represented by the following formula, as a treatment agent which has a perfluorooxyalkylene moiety with no branch structure in the main chain,

wherein Rf is a divalent linear perfluoropolyether group, R is an alkyl group having 1 to 4 carbon atoms or a phenyl group, X is a hydrolyzable group, 1 is an integer of from 0 to 2, m is an integer of from 1 to 5, and a is 2 or 3.
Lenses and anti-reflection films treated with the aforesaid perfluoropolyether-modified silane are good in stainproofness, easy removal of fouling, lubricity and a releasing property, compared to the perfluoropolyether-modified silane having a branch structure. Further, abrasion resistance is superior to the prior perfluoropolyether-modified silane, because the both terminals thereof are fixed on a substrate. However, the lubricity intrinsic to this perfluoropolyether is not well exhibited due to the both terminals being fixed on a substrate, so that further improvement is required. Further, unreacted terminal moieties remaining after curing reduce water- and oil-repellency, releasing property and lubricity. Therefore, improvement on these properties by decreasing unreacted terminal moiety is desired.
Japanese Patent Application Laid-Open No. 2007-297589 discloses a perfluoropolyether-modified silane represented by the following formula, as a treatment agent which has improved lubricity,(Z2Q)βRf(QZ1Aα)2-β
wherein Rf is a divalent perfluoroether-containing group, Q is a divalent organic group, Z1 and Z2 are organopolysiloxane moieties, A is a monovalent group having a terminal reactive silyl group, α is an integer of from 1 to 8, and β is the number larger than 0 and less than 2.
However, this compound does not have a terminal fluorinated group, so that its water- and oil-repellency, dynamic friction coefficient and releasing property are inferior.
Patent literature 1: Japanese Patent Application Laid-Open No. Sho-58-167597
Patent literature 2: Japanese Patent Application Laid-Open No. 2000-143991
Patent literature 3: Japanese Patent Application Laid-Open No. 2003-238577
Patent literature 4: Japanese Patent Application Laid-Open No. 2007-297589